将一条记录分成多条

Question

我需要一个查询来改变这个：

col1 col2 col3
1    2    abc
3    4    cd
4    5    null

到这里

col1 col2 col3
1    2    a
1    2    b
1    2    c
3    4    c
3    4    d
4    5    NULL

谢谢。

Answer 1

这样试试

编辑流水号的较短语法

EDIT2 JamieD77 的评论将TOP 包含在数字的创建中

CREATE FUNCTION dbo.SingleChars(@SomeText NVARCHAR(MAX))
RETURNS TABLE
AS
RETURN
WITH nr10 AS
(
    SELECT * FROM (VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) AS tbl(A)
)
,RunningNumbers AS
(
    SELECT TOP (ISNULL(LEN(@SomeText),0)) ROW_NUMBER() OVER(ORDER BY (SELECT(NULL))) AS Nmbr FROM nr10,nr10 AS a,nr10 AS b,nr10 AS c,nr10 AS d,nr10 AS e,nr10 AS f,nr10 AS g
)
SELECT SUBSTRING(@SomeText,Nmbr,1) AS TheCharacter
      ,ASCII(SUBSTRING(@SomeText,Nmbr,1)) AS ASCII_Code
FROM RunningNumbers;

测试

SELECT * FROM dbo.SingleChars('This is a test');

结果

T   84
h   104
i   105
s   115
    32
i   105
s   115
    32
a   97
    32
t   116
e   101
s   115
t   116

现在你的问题

DECLARE @tbl TABLE(col1 INT, col2 INT, col3 VARCHAR(100));
INSERT INTO @tbl VALUES(1,2,'abc'),(3,4,'cd'),(4,5,NULL);

SELECT col1,col2,sc.TheCharacter
FROM @tbl
OUTER APPLY dbo.SingleChars(col3) AS sc;

结果

1   2   a
1   2   b
1   2   c
3   4   c
3   4   d
4   5   NULL

Answer 2

在 MSSQL 中，您可以使用 recursive CTE。每一步只需要一个左字母：

WITH T1 as 
(
  SELECT col1,col2,LEFT(col3,1) as col4, SUBSTRING(col3,2,10000) as col3 
         FROM Table1
  UNION ALL
  SELECT col1,col2,LEFT(col3,1) as col4, SUBSTRING(col3,2,10000) as col3 
         FROM T1 WHERE Col3 <> ''
)

SELECT col1,col2,col4 FROM T1 ORDER BY col1,col2;

还有一个查询：

WITH T1 as 
(
  SELECT col1,col2,LEFT(col3,1) as col4, col3, 2 as nextPoint  
         FROM Table1
  UNION ALL
  SELECT col1,col2,SUBSTRING(col3,nextPoint,1) as col4, col3, 
         nextPoint+1 as nextPoint  
         FROM T1 WHERE LEN(col3)>=nextPoint
)
SELECT col1,col2,col4 FROM T1 ORDER BY col1,col2;